In the summer of 1933, Stowe visited Nazi Germany. Shocked by its militarism, he wrote a series of critical articles that were not published as the articles were seen as too alarmist. Stowe published the articles in a book, Nazi Germany Means War; it was, however, not a success.

When World War II started in Europe in 1939, he worked as a war correspondent for the Chicago Daily News and the New York Post. He happened to be in Oslo on April 9, 1940 and therefore witnessed the German invasion, as well as the general confusion within the Norwegian forces, administration, and Allied Expeditionary Forces. Stowe "revealed the collaboration of Norwegian Vidkun Quisling in helping the Nazis seize Oslo without a shot."[4] In 1942 Stowe as a war correspondent visited Moscow and traveled to the front lines of the still retreating troops of USSR. His travel companion and guide was Ilya Ehrenburg, a Russian-Jewish-Soviet war journalist. Stowe's book They Shall Not Sleep gives a rare insider view of an American journalist on the Soviet Army, and the events of the war from the Soviet side of the front.

Stowe's critical reportage was claimed to be one of the influences that helped bring down Prime Minister Neville Chamberlain in the United Kingdom. His writings also gave the Norwegian government-in-exile considerable problems as they tried to organise the resistance after Norway had been occupied.[citation needed] It was quite often an image-problem, that C. J. Hambro worked actively towards correcting, working in exile.

Stowe kept on working as a correspondent during the war, covering 44 countries on four continents.[5] After the war, Stowe was director of Radio Free Europe's News and Information Service.

In 1955, he became a professor of journalism at the University of Michigan in Ann Arbor. During his tenure, he alternated between teaching one semester each academic year and working as an editor and staff writer for Reader's Digest. During this time he heard about a pioneering settler in British Columbia named Ralph Edwards and spent 12 days in his remote cabin interviewing him for the book Crusoe of Lonesome Lake (1957) which became one of Stowe's most popular books.

He taught at the university until he retired in 1970, after which he was a professor emeritus of journalism. He remained in Ann Arbor until his death.